EVALUATING STANDARD CONDITIONS FOR MEASURING THE HYDROPHOBICITY OF ACTIVATED SLUDGE BY BACTERIAL ADHESION TO HYDROCARBONS (BATH)

摘要

Bacterial adhesion to hydrocarbons (BATH) is one of the simple and practical methods to measure the hydropho-bicity of activated sludge. This method is strongly dependent on the experimental conditions; however, in the current field there is no standard methodology. This study is an attempt to evaluate the test parameters (i.e. wavelength, standing time, choice of hydrocarbon and aqueous solution, and their volume) on BATH using activated sludge samples. Results show that the relative hydrophobicity of activated sludge was greater and more stable at 600 nm than at 400 nm, and a minimum standing time of 20 min gave stable results. Moreover, n-octane was more suitable as the hydrophobic phase compared to n-hexane and n-hexadecane, and phosphate-urea-magnesium (PUM) buffer is a better choice than deionised water for the aqueous phase. The volume ratio of the hydrophobic to the aqueous solution is suggested to 1/5. An optimized procedure is recommended.